    <div class="refentry" id="glBeginTransformFeedback">
      <div class="titlepage"></div>
      <div class="refnamediv">
        <h2>Name</h2>
        <p>glBeginTransformFeedback — start transform feedback operation</p>
      </div>
      <div class="refsynopsisdiv">
        <h2>C Specification</h2>
        <div class="funcsynopsis">
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">void <strong class="fsfunc">glBeginTransformFeedback</strong>(</code>
              </td>
              <td>GLenum <var class="pdparam">primitiveMode</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
        </div>
        <div class="funcsynopsis">
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">void <strong class="fsfunc">glEndTransformFeedback</strong>(</code>
              </td>
              <td><var class="pdparam">void</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
        </div>
      </div>
      <div class="refsect1" id="parameters">
        <h2>Parameters for <code class="function">glBeginTransformFeedback</code></h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>primitiveMode</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specify the output type of the primitives that will be recorded into the
                    buffer objects that are bound for transform feedback.
                </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1" id="description">
        <h2>Description</h2>
        <p>
            Transform feedback mode captures the values of varying variables written by the vertex shader.
            Transform feedback is said to be active after a call to <code class="function">glBeginTransformFeedback</code>
            until a subsequent call to <code class="function">glEndTransformFeedback</code>.
            Transform feedback commands must be paired. An implicit <a class="citerefentry" href="glResumeTransformFeedback"><span class="citerefentry"><span class="refentrytitle">glResumeTransformFeedback</span></span></a>
            is performed by <code class="function">glEndTransformFeedback</code> if the transform feedback is paused.
            Transform feedback is restricted to non-indexed <code class="constant">GL_POINTS</code>, <code class="constant">GL_LINES</code>, and
            <code class="constant">GL_TRIANGLES</code>.
        </p>
        <p>
            While transform feedback is active the <em class="parameter"><code>mode</code></em> parameter to
            <a class="citerefentry" href="glDrawArrays"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a> must exactly match the
            <em class="parameter"><code>primitiveMode</code></em> specified by <code class="function">glBeginTransformFeedback</code>.
        </p>
      </div>
      <div class="refsect1" id="errors">
        <h2>Errors</h2>
        <p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glBeginTransformFeedback</code> is executed
            while transform feedback is active.
        </p>
        <p>
            <code class="constant">GL_INVALID_ENUM</code> is generated by <code class="function">glBeginTransformFeedback</code> if <em class="parameter"><code>primitiveMode</code></em>
            is not one of  <code class="constant">GL_POINTS</code>, <code class="constant">GL_LINES</code>, or <code class="constant">GL_TRIANGLES</code>.
        </p>
        <p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glEndTransformFeedback</code> is executed
            while transform feedback is not active.
        </p>
        <p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated by <a class="citerefentry" href="glDrawArrays"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a>
            and <a class="citerefentry" href="glDrawArraysInstanced"><span class="citerefentry"><span class="refentrytitle">glDrawArraysInstanced</span></span></a> if transform feedback is active
            and <em class="parameter"><code>mode</code></em> does not exactly match <em class="parameter"><code>primitiveMode</code></em>.
        </p>
        <p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated by <a class="citerefentry" href="glDrawElements"><span class="citerefentry"><span class="refentrytitle">glDrawElements</span></span></a>,
            <a class="citerefentry" href="glDrawElementsInstanced"><span class="citerefentry"><span class="refentrytitle">glDrawElementsInstanced</span></span></a>, and
            <a class="citerefentry" href="glDrawRangeElements"><span class="citerefentry"><span class="refentrytitle">glDrawRangeElements</span></span></a> if transform feedback is active and not paused.
        </p>
        <p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated by <code class="function">glBeginTransformFeedback</code> if any binding
            point used in transform feedback mode does not have a buffer object bound. In interleaved mode, only the first buffer
            object binding point is ever written to.
        </p>
        <p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated by <code class="function">glBeginTransformFeedback</code> if no binding
            points would be used, either because no program object is active of because the active program object has specified
            no varying variables to record.
        </p>
      </div>
      {$pipelinestall}{$examples}
      <div class="refsect1" id="versions">
        <h2>API Version Support</h2>
        <div class="informaltable">
          <table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
            <colgroup>
              <col style="text-align: left; "/>
              <col style="text-align: center; " class="firstvers"/>
              <col style="text-align: center; "/>
              <col style="text-align: center; " class="lastvers"/>
            </colgroup>
            <thead>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; ">

            </th>
                <th style="text-align: center; border-bottom: 2px solid ; " colspan="3">
                <span class="bold"><strong>OpenGL ES API Version</strong></span>
            </th>
              </tr>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>Function Name</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.0</strong></span>
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.1</strong></span>
            </th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                  <code class="function">glBeginTransformFeedback</code>
                </td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
                <td style="text-align: center; border-bottom: 2px solid ; ">✔</td>
              </tr>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; ">
                  <code class="function">glEndTransformFeedback</code>
                </td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; ">✔</td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1" id="seealso">
        <h2>See Also</h2>
        <p>
            <a class="citerefentry" href="glPauseTransformFeedback"><span class="citerefentry"><span class="refentrytitle">glPauseTransformFeedback</span></span></a>,
            <a class="citerefentry" href="glResumeTransformFeedback"><span class="citerefentry"><span class="refentrytitle">glResumeTransformFeedback</span></span></a>
        </p>
      </div>
      <div class="refsect1" id="Copyright">
        <h2>Copyright</h2>
        <p>
            Copyright © 2010-2014 Khronos Group.
            This material may be distributed subject to the terms and conditions set forth in
            the Open Publication License, v 1.0, 8 June 1999.
            <a class="link" href="https://opencontent.org/openpub/" target="_top">https://opencontent.org/openpub/</a>.
        </p>
      </div>
    </div>
